Scale base



FIG. 1 is a top plan view of a scale base showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side elevational view thereof, the right side view being a mirror image thereof;

FIG. 4 is a bottom plan view thereof; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a scale base, as shown and described. 